The coupling and configuration of two interfaces in a communication system is generally critical to the operation of devices whose interfaces are being coupled. In some instances, improper coupling or configuration may result in one or more of damaged equipment, malfunctioning equipment and system failure. Particularly in systems which lack redundancy, improper coupling or configuration may, in certain instances, render a system or specific sub-system inoperable. In order to mitigate the effects of improper coupling and configuration, various techniques and methodologies have been implemented. Automatic media dependent interface (MDI) crossover (Auto-MDIX), Ethernet@wirespeed and cable diagnostics, for example, provide ways for eliminating or otherwise mitigating certain effects that result from improper coupling or configuration.
In a typical 4-pair conductor or wire system, auto-MDIX may be adapted to automatically detect the order of media pairs 1 and 2 and in certain instances, auto-MDIX may reconfigure only certain channels so as to properly re-assign the transmit/receive media pairs to these channels. Auto-MDIX may also be adapted to reconfigure channel ordering for certain channels in order to mitigate the effects of improper interfacing and/or configuration. In 1000 Base-T mode for example, auto-MDIX may reconfigure the operational mode of media pairs 3 and 4 in accordance with or dependent on the order of media pairs 1 & 2. Auto-MDIX may eliminate a need for crossover cables which may be utilized between hubs and routers, for example. Finally, auto-MDIX may simplify installation in certain applications since the wiring order of a cable plant does not have be known.
Notwithstanding, Auto-MDIX is limited to reconfiguring only media pairs 1 and 2 and media pairs 3 and 4. In particular, auto-MDIX relies on a basic assumption that media pairs 1 & 2 are wired respectively and media pairs 3 & 4 are wired respectively. Accordingly, a major drawback with auto-MDIX is that auto-MDIX does not operate on other combinations of wiring configurations. For example, auto-MDIX does not operate on media pairs 1 and 3 or media pairs 2 and 4 and as a result, may be able to reconfigure and/or correct an improper installation involving media pairs 1 and 3 and media pairs 2 and 4. Another disadvantage of auto-MDIX is that it operated on a basic assumption that media pairs 1 and 2 are wired respectively and media pairs 3 & 4 are wired respectively.
On the contrary, Ethernet@wirespeed provides an algorithm that is adapted to detect the conditions on the media and/or the coupling interface and to select and implement an appropriate methodology for mitigating the effects of improper cabling or interfacing. In this regard, Ethernet@wirespeed may be adapted to automatically down shift or reduce transmission speed whenever optimal transmission cannot be maintained or supported due to impairments in the channel characteristics, which may be caused by improper cabling or interfacing. Ethernet@wirespeed may be particularly useful in cases where channel or media characteristics have degraded but the channel or media is still required for providing communication. For example, in 1000 Base-T applications, the conditions on the media may deteriorate to a point where 1000 Base-T operational speeds cannot be sustained, but the channel cannot be taken out of service because it is needed for providing data communication. As a result, 10/100 Base-T service may be provided. One drawback with Ethernet@wirespeed is that it does not operate on a broken or damaged media pair 1 or media pair 2 in a cable plant. Moreover, Ethernet@wirespeed does not have the capability to reconfigure wire pairs in order to utilize other good pairs in the cable plant. For example, in a case where media pair 3 or pair 4 may be unused, Ethernet@wirespeed does not have the capability to reconfigure media pair 3 or media pair 4 for communication.
In contrast, cable diagnostics may be adapted to provide information pertaining to the quality of a cable plant. In this regard, cable diagnostics may detect whether there is, for example, an open, short or proper termination on the cable or media. Cable diagnostics may be adapted to determine, for example, the length of the cable plant or media, and provide information regarding a location of an impedance mismatch in the cable plant. Notwithstanding, cable diagnostics does not have the capability to determine whether the cable plant has been incorrectly installed. For example, in a case where media pair 1 and media pair 3 are swapped but all the termination points are correct, cable diagnostics does not have the capability to detect and report the swapped cable condition. In this case, cable diagnostics will report that all is copasetic, even though media pair 1 has been swapped with media pair 3.
Various standards such as 10 Base-T, 100 Base-T and 1000 Base-T have been developed to provide communications over unshielded twisted pair. For example, 1000 Base-T was developed to provide data communication at speeds of the order of 1 Gigabits per second (Gbps) over category-5 (CAT-5) unshielded twisted pair (UTP) wire or cable. The 1000 Base-T standard defines a five (5) level pulse amplitude modulated signal that may be transmitted over the CAT-5 wiring.
In this regard, a 1000 Base-T transceiver may be adapted to transmit data at a rate of 125 megasymbols over each pairs in a 4 media pair in a CAT-5 wire or cable. Since each 125 megasymbol carries 250 megabits per second, the effective rate over four (4) media pairs is one gigabit per second.
To mitigate the effects of interference such as near-end crosstalk, far-end crosstalk, echo and attenuation resulting from use of the unshielded twisted pair, a 1000 Base-T transceiver may include an analog front end (AFE). The analog front end may include, but is not limited to, analog-to-digital converters (ADCs), digital-to-analog converters (DACs) and amplifiers. These devices that may be required to implement the analog front end may require additional chip area, which increases the size of the transceiver chip.
FIG. 1 is a block diagram of a conventional auto-MDIX system, which utilizes four (4) media pairs. Referring to FIG. 1, there is shown a first AFE 102 which is a 10/100/1000 Base-T AFE, a second AFE 104 which is a 10/100/1000 Base-T AFE, a third AFE 106 which is a 1000 Base-T AFE, a fourth AFE 108 which is a 1000 Base-T AFE, a first auto-MDIX controller 110 and a second auto-MDIX controller 112. The first AFE 102 may be coupled to a first media pair and the second AFE 104 may be coupled to a second media pair. The third AFE 106 may be coupled to a third media pair and the fourth AFE 108 may be coupled to a fourth media pair. The first auto-MDIX controller 110 is coupled to a channel A transmit/receive data signal and a channel B transmit/receive data signal. The second auto-MDIX controller 112 is coupled to a channel C transmit/receive data signal and a channel D transmit/receive data signal. Although AFEs 106, 108 are represented as 1000 Base-T AFEs, they may be configured to provide additional 10/100 Base-T functionality.
Notwithstanding, in the auto-MDIX configuration of FIG. 1, the first controller 110 operates independent of the second controller 112. The first controller 110 may only control the coupling or cross-connect of channel A or channel B to any of only the first media pair or the second media pair. Similarly, the second controller may only control the coupling or cross-connect of channel C or channel D to any of only the first media pair or the second media pair. Accordingly, the first controller 110 cannot cross-connect channel A or channel B to any of the third media pair or the fourth media pair and the second controller 112 cannot cross connect channel C or channel D to any of the first media pair or the second media pair.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.